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{{Short description|German aviation engineer and inventor (1885–1961)}}
{{Infobox engineer
{{Infobox engineer
|image = Anton Flettner 01.jpg
|image = Anton Flettner 01.jpg
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|caption = Anton Flettner
|caption = Anton Flettner
|name = Anton Flettner
|name = Anton Flettner
|nationality = Germany
|nationality = German
|birth_date = November 1, 1885
|birth_date = 1 November 1885
|birth_place = [[Hattersheim am Main]], Germany
|birth_place = [[Hattersheim am Main]], Germany
|death_date = {{d-da|December 29, 1961|November 1, 1885}}
|death_date = {{death-date and age|29 December 1961|1 November 1885}}
|death_place = [[New York City]]
|death_place = [[New York City]], US
|education =
|education =
|spouse =
|spouse =
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|significant_awards =
|significant_awards =
}}
}}
'''Anton Flettner''' (November 1, 1885 – December 29, 1961) was a German [[Aerospace engineering|aviation engineer]] and [[inventor]].<ref name="britannica">{{cite journal|title=Anton Flettner|journal=The New York Times|date=December 30, 1961|issue=Obituary}}</ref> Born in Eddersheim (today a district of [[Hattersheim am Main]]), Flettner made important contributions to airplane, helicopter, vessel, and automobile designs.<ref name=britannica /><ref name="flettner">{{cite web|title=FLETTNER, Anton aus Eddersheim am Main|url=http://www.duchmann.net/AntonFLETTNER.htm|website=duchmann.net|publisher=Duchmann}}</ref><ref name="flettnerventilator">{{cite web|title=Flettner Ventilator|url=http://www.flettner.co.uk/about/|website=flettner.co.uk}}</ref>
'''Anton Flettner''' (1 November 1885 – 29 December 1961) was a German [[Aerospace engineering|aviation engineer]] and [[inventor]].<ref name="britannica">{{cite journal|title=Anton Flettner|journal=The New York Times|date=December 30, 1961|issue=Obituary}}</ref> Born in [[Hattersheim am Main#Eddersheim|Eddersheim]] (today a district of Hattersheim am Main), Flettner made important contributions to airplane, helicopter, vessel, and automobile designs.<ref name=britannica /><ref name="flettner">{{cite web|title=FLETTNER, Anton aus Eddersheim am Main|url=http://www.duchmann.net/AntonFLETTNER.htm|website=duchmann.net|publisher=Duchmann}}</ref><ref name="flettnerventilator">{{cite web|title=Flettner Ventilator|url=http://www.flettner.co.uk/about/|website=flettner.co.uk}}</ref>


After serving Germany in both World Wars, Anton Flettner emigrated to the United States post [[World War II]] as a consultant to the office of Naval Research at the [[United States Navy]].<ref name="helis">{{cite web|last1=Graven|first1=Eric|title=Anton Flettner|url=http://www.helis.com/pioneers/f_flet.php|website=Helis.com|publisher=The New York Times}}</ref>
After serving Germany in both World Wars, Anton Flettner emigrated to the United States post [[World War II]] as a consultant to the office of Naval Research at the [[United States Navy]].<ref name="helis">{{cite web|last1=Graven|first1=Eric|title=Anton Flettner|url=http://www.helis.com/pioneers/f_flet.php|website=Helis.com|publisher=The New York Times}}</ref>


Anton Flettner attended the Fulda State Teachers College in Fulda, Germany.<ref name="luftwaffe">{{cite book|last1=Lepage|first1=Jean-Denis G.G.|title=Aircraft of the Luftwaffe, 1935D1945: An Illustrated Guide|date=February 5, 2009|publisher=McFarland|isbn=978-0786439379|pages=23–24}}</ref> He was the village teacher in Pfaffenwiesbach from 1906 to 1909.<ref name="helis" /> Flettner subsequently taught high school mathematics and physics in Frankurt, where he developed ideas that would assist Germany in World War I.<ref name="luftwaffe" />
Anton Flettner attended the Fulda State Teachers College in Fulda, Germany.<ref name="luftwaffe">{{cite book|last1=Lepage|first1=Jean-Denis G.G.|title=Aircraft of the Luftwaffe, 1935D1945: An Illustrated Guide|date=February 5, 2009|publisher=McFarland|isbn=978-0786439379|pages=23–24}}</ref> He was the village teacher in Pfaffenwiesbach from 1906 to 1909.<ref name="helis" /> Flettner subsequently taught high school mathematics and physics in Frankfurt, where he developed ideas that would assist Germany in World War I.<ref name="luftwaffe" />


Flettner revolutionized the art of harnessing the wind, used essentially in an unaltered form for thousands of years—the canvas sail—by a modern machine—the Flettner [[Rotor ship]]—that could permit ocean liners to reduce their crews by two-thirds and save 90 percent in fuel.<ref name="meinwegzumrotor">{{cite web|title=Mein Weg zum Rotor|url=https://www.abebooks.com/book-search/title/mein-weg-zum-rotor/|website=abebooks.com|publisher=F.O. Willhoft}}</ref><ref name="magnuseffectpropulsion">{{cite journal|last1=Seybold|first1=G.B.|title=A Sailing Ship Without Sails: New Wonder of the Seas|journal=Popular Science Monthly|volume=February 1925|url=http://www.homepages.ed.ac.uk/shs/Climatechange/Flettner%20ship/Popular%20Science%201st%20American.htm}}</ref>
Flettner developed a new method of harnessing the wind: the Flettner [[Rotor ship]]. It could permit ocean liners to reduce their crews by two-thirds and save 90 percent in fuel.<ref name="meinwegzumrotor">{{cite web|title=Mein Weg zum Rotor|url=https://www.abebooks.com/book-search/title/mein-weg-zum-rotor/|website=abebooks.com|publisher=F.O. Willhoft}}</ref><ref name="magnuseffectpropulsion">{{cite journal|last1=Seybold|first1=G.B.|title=A Sailing Ship Without Sails: New Wonder of the Seas|journal=Popular Science Monthly|volume=February 1925|url=http://www.homepages.ed.ac.uk/shs/Climatechange/Flettner%20ship/Popular%20Science%201st%20American.htm}}</ref>


== World War I ==
== World War I ==
From 1914 to 1918 Anton Flettner worked at the German Ministry for War in the development of remote controls for air, water, and land vehicles.<ref name="aeronautical">{{cite book|last1=Hirschel|first1=Ernst Heinrich|last2=Prem|first2=Horst|last3=Madelung|first3=Gero|title=Aeronautical Research in Germany: From Lilienthal until Today|url=https://books.google.com/books?id=eJ7oCAAAQBAJ&pg=PA299&dq=aeronautical+anton+flettner#v=onepage|publisher=Springer|isbn=9783642184840|date=2012-12-06}}</ref> While employed under the aegis of [[Ferdinand von Zeppelin|Graf Zeppelin]], Flettner also developed pilotless aircraft projects.<ref name=britannica /><ref name="largescaleplanes">{{cite web|title=Flettner Fl 282 "Kolibri" 1940|url=http://www.aviastar.org/helicopters_eng/flettner_kolibri.php|website=aviastar.org|publisher=Aviastar}}</ref>
From 1914 to 1918 Anton Flettner worked at the German Ministry for War in the development of remote controls for air, water, and land vehicles.<ref name="aeronautical">{{cite book|last1=Hirschel|first1=Ernst Heinrich|last2=Prem|first2=Horst|last3=Madelung|first3=Gero|title=Aeronautical Research in Germany: From Lilienthal until Today|url=https://books.google.com/books?id=eJ7oCAAAQBAJ&q=aeronautical+anton+flettner&pg=PA299|publisher=Springer|isbn=9783642184840|date=2012-12-06}}</ref> While employed under the aegis of [[Ferdinand von Zeppelin|Graf Zeppelin]], Flettner also developed pilotless aircraft projects.<ref name=britannica />


At the age of 29, Flettner presented his first invention, a steerable torpedo, to the Kriegsmarine (German Imperial Navy) of [[World War I]].<ref name="flettner" /> This, and his next invention, a remote-controlled combat car, which was presented to the Heer (German Army), were rejected because they were not considered to be technically feasible.<ref name="flettner" /> However, Flettner's efforts culminated in the prototype Siemens Schuckert Werke 1000&nbsp;kg wire guided air to surface missile of 1918.<ref name="largescaleplanes" />
At the age of 29, Flettner presented his first invention, a steerable torpedo, to the Kriegsmarine (German Imperial Navy) of [[World War I]].<ref name="flettner" /> This, and his next invention, a remote-controlled combat car, which was presented to the Heer (German Army), were rejected because they were not considered to be technically feasible.<ref name="flettner" /> However, Flettner's efforts culminated in the prototype Siemens Schuckert Werke 1000&nbsp;kg wire guided air to surface missile of 1918.


During [[World War I]], Flettner developed the [[servo tab]] / anti-servo tab.<ref name="neam">{{cite web|title=Anton Flettner|url=http://www.neam.co.uk/helicopters/flettner.html|website=NEAM}}</ref> The [[servo tab]] evolved into the "trim tab" which is still in use on all airplanes and many large vessels.<ref name=britannica /><ref name=neam /> Trim tabs are extremely useful in moving large rudders on vessels with vastly reduced power.<ref name=britannica /><ref name=neam />
During [[World War I]], Flettner developed the [[servo tab]] / anti-servo tab.<ref name="neam">{{cite web|title=Anton Flettner|url=http://www.neam.co.uk/helicopters/flettner.html|website=NEAM}}</ref><ref name="NY Times Obituary">{{cite journal |title=ANTOH FLETTNER, INVENTOR, WAS 76; Developer of Controls Used in Ships and Planes Dies |journal=The New York Times |date=30 December 1961 |url=https://www.nytimes.com/1961/12/30/archives/antoh-flettner-inventor-was-76-developer-of-controls-used-in-ships.html |access-date=11 September 2024}}</ref> The [[servo tab]] evolved into the "trim tab" which is still in use on all airplanes and many large vessels.<ref name=britannica /><ref name=neam /> Trim tabs are extremely useful in moving large rudders on vessels with vastly reduced power.<ref name=britannica /><ref name=neam />


[[File:Buckau Flettner Rotor Ship LOC 37764u.jpg|thumb|The [[Flettner rotor]] ship ''Buckau''|300px]]
[[File:Buckau Flettner Rotor Ship LOC 37764u.jpg|thumb|The [[Flettner rotor]] ship ''Buckau''|300px]]


==Savonius collaboration==
== Post World War I ==
In 1923, Finnish architect [[Sigurd Johannes Savonius]] took interest in Flettner's rotor ship, and the two began a collaboration. By the next year, the architect had invented the [[Savonius wind turbine]], and by 1930 had patented a ventilation device based on the wind turbine.<ref>{{cite web |author=Sigurd J. Savonius |title=Durch Luftströmung angetriebene Vorrichtung zur Ventilation von geschlossenen Räumen oder zur Verbesserung, bezw. Erhaltung eines Schornsteinzuges |url=https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=CH000000147730A}}</ref> The patent was later acquired by Flettner's firm Flettner Ventilator Limited, which still manufactures modern versions of the device in Britain.<ref>[http://www.flettner.co.uk/ Flettner Ventilator Limited]</ref><ref name="Magnus Effect Overview for US Navy">{{cite web |last1=Borg |first1=John |title=The Magnus Effect - an overview of its past and future practical applications |url=https://apps.dtic.mil/sti/pdfs/ADA165902.pdf |website=Defense Technical Information Center (.mil) |publisher=Prepared by the Borg/Luther Group for Naval Sea Systems Command Department of the Navy |access-date=11 September 2024 |date=1985}}</ref> It has been widely used on buses, vans, boats, railroad cars, campervans, and trucks to assist cooling in warm weather.
Following [[World War I]], Flettner was named Managing Director of the Institute for Aero and Hydro Dynamics in [[Amsterdam]].<ref name="helis" /> He held that post until 1931.<ref name="helis" /> In the 1920s, Flettner also invented the famous [http://www.toplicht.de/shop/fenster-bullauge-luke-und-luefter/windhutze-und-luefter/rotationsluefter/rotationsluefter-flettner-tcx-2 Flettner rotary ventilator], which was widely used on buses, vans, boats, railroad cars, campervans, and trucks to assist cooling without the use of energy.<ref name="flettner" /> Modern derivatives of his ventilator are still manufactured in Britain by [http://www.flettner.co.uk/ Flettner Ventilator Limited].<ref name="flettner" />


== Other post-World-War-I work ==
With assistance from [[Albert Betz]] (German physicist), [[Jakob Ackeret]] (Swiss aeronautical engineer), [[Ludwig Prandtl]] (German engineer), and [[Albert Einstein]] (German theoretical physicist), Anton Flettner constructed an experimental rotor vessel ([[Buckau]] later renamed the [[Baden-Baden]]) in October 1924 at the [[Friedrich Krupp Germaniawerft]].<ref name="thiiink">{{cite web|title=History of windpower|url=http://www.thiiink.com/history-of-flettner-rotor/|website=Thiiink.com}}</ref> The [[Buckau]] was a schooner refitted with two rotating 50-foot cylinders and was the first vessel built with a propulsion system based on the [[Magnus effect]].<ref name="thiiink" /> Flettner came upon the idea while at the beach with his wife.<ref name="magnuseffectpropulsion" /> Flettner used sand, flowing over his rotating hand, to describe the [[Magnus effect]] and realized its potential for sail propulsion.<ref name="magnuseffectpropulsion" /> The [[Flettner ship|''Baden-Baden'']] crossed the [[Atlantic Ocean|Atlantic]] in 1926.<ref name="helis" /> It could outsail normal schooners under moderate to heavy winds, but it was destroyed by a storm in 1931.<ref name="researchgate">{{cite web|title=Anton Flettner's first rotor ship, the Baden-Baden, crossed the Atlantic in 1926|url=https://www.researchgate.net/figure/23223631_fig2_Figure-5-Anton-Flettner's-first-rotor-ship-the-Baden-Baden-crossed-the-Atlantic-in|website=Researchgate.net}}</ref> A commercial ship, the ''Barbara'' [[Rotor ship]], was also built and sailed to the United States.<ref name="researchgate" />
Following [[World War I]], Flettner was named managing director of the Institute for Aero and Hydro Dynamics in [[Amsterdam]].<ref name="helis" /> He held that post until 1931.<ref name="helis" />


With assistance from German physicist [[Albert Betz]], Swiss aeronautical engineer [[Jakob Ackeret]], German engineer [[Ludwig Prandtl]] and German theoretical physicist [[Albert Einstein]], Anton Flettner constructed an experimental rotor vessel, the ''Buckau'', later renamed the ''Baden-Baden'', in October 1924 at the [[Friedrich Krupp Germaniawerft]].<ref name="thiiink">{{cite web|title=History of windpower|url=http://www.thiiink.com/history-of-flettner-rotor/|website=Thiiink.com}}</ref> The ''Buckau'' was a schooner refitted with two rotating 50-foot cylinders and was the first vessel built with a propulsion system based on the [[Magnus effect]].<ref name="thiiink" /> Flettner came upon the idea while at the beach with his wife.<ref name="magnuseffectpropulsion" /> Flettner used sand, flowing over his rotating hand, to describe the Magnus effect and realized its potential for sail propulsion.<ref name="magnuseffectpropulsion" /> The ''Baden-Baden'' crossed the [[Atlantic Ocean|Atlantic]] in 1926.<ref name="helis" /> It could outsail normal schooners under moderate to heavy winds, but was destroyed by a storm in 1931.<ref name="researchgate">{{cite web|title=Anton Flettner's first rotor ship, the ''Baden-Baden'', crossed the Atlantic in 1926|url=https://www.researchgate.net/figure/23223631_fig2_Figure-5-Anton-Flettner's-first-rotor-ship-the-Baden-Baden-crossed-the-Atlantic-in|website=Researchgate.net}}</ref> A commercial [[rotor ship]], the ''Barbara'', was also built, and sailed to the United States.<ref name="researchgate" />
In 1926, Anton Flettner shifted his focus to aviation in founding his own company, the Anton Flettner Aircraft Corporation in Berlin, aiming at the application of the Flettner-rotor as a wing replacement on large wind turbines.<ref name="aeronautical" /><ref name=neam /> In 1935, Flettner built a German night reconnaissance and anti-submarine [[autogyro]] called the [[Fl 184]].<ref name=neam /><ref name="flettner fl 184">{{cite web|title=Flettner Fl 184 reconnaissance helicopter, prototype|url=http://www.nevingtonwarmuseum.com/flettner-fl-184.html|website=newingtonwarmuseum.com|publisher=Newington War Museum}}</ref> Flettner followed this accomplishment by building the [[Flettner Fl 185]] in 1936, an experimental [[Germany|German]] [[gyrodyne]], which could fly as both a [[helicopter]] and as a [[gyroplane]].<ref name="fl185">{{cite web|title=Flettner.Fl 185 1938|url=http://www.aviastar.org/helicopters_eng/flettner-185.php|website=aviastar.org|publisher=Aviastar}}</ref>

In 1926, Anton Flettner shifted his focus to aviation in founding his own company, the Anton Flettner Aircraft Corporation in Berlin, aiming at the application of the Flettner-rotor as a wing replacement on large wind turbines.<ref name="aeronautical" /><ref name=neam /> In 1935, Flettner built a German night reconnaissance and anti-submarine [[autogyro]] called the [[Fl 184]].<ref name=neam /><ref name="flettner fl 184">{{cite web|title=Flettner Fl 184 reconnaissance helicopter, prototype|url=http://www.nevingtonwarmuseum.com/flettner-fl-184.html|website=newingtonwarmuseum.com|publisher=Newington War Museum}}</ref> Flettner followed this accomplishment by building the [[Flettner Fl 185]] in 1936, an experimental [[Germany|German]] [[gyrodyne]], which could fly as both a [[helicopter]] and as a [[gyroplane]].


In 1938 Flettner, together with [[Kurt Hohenemser]], built the [[Flettner Fl 265]].<ref name="flettner" /> The [[Flettner Fl 265]] as the likely pioneering example of a twin-lift rotor [[synchropter]], addressed the problem of torque compensation as the first helicopter with [[intermeshing rotors]] (Flettner double rotor).<ref name="flettner" />
In 1938 Flettner, together with [[Kurt Hohenemser]], built the [[Flettner Fl 265]].<ref name="flettner" /> The [[Flettner Fl 265]] as the likely pioneering example of a twin-lift rotor [[synchropter]], addressed the problem of torque compensation as the first helicopter with [[intermeshing rotors]] (Flettner double rotor).<ref name="flettner" />
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== World War II ==
== World War II ==
During [[World War II]], Anton Flettner headed [http://www.wehrmacht-history.com/manufacturers/flettner-aircraft-manufacturer.htm Flettner Flugzeubau GmbH], which specialized in reconnaissance helicopters for the German Luftwaffe (Air Force).<ref name=britannica />
During [[World War II]], Anton Flettner headed [[Flettner|Flettner Flugzeugbau GmbH]], which specialized in reconnaissance helicopters for the German Luftwaffe (Air Force).<ref name=britannica />


Flettner's helicopter inventions were financed from wealth acquired from his ventilator business, a company that was enhanced by the skill of his wife, Lydia Freudenberg Flettner.<ref name=flettner/> Anton Flettner built his helicopters for the German military, primarily for navy spotter use. Although his wife was Jewish,<ref name="flettner fl-282v21 kolibri">{{cite web|title=The Flettner Fl-282 V21 Kolibri|url=https://sites.google.com/site/skynetairplanes/helicopters/the-flettner-fl-282-v21-kolibri|website=Skynet Airplanes}}</ref> he held a personal relationship with the head of gestapo, [[Heinrich Himmler]]. Himmler had Flettner's wife and family escorted safely to Sweden for the duration of the war.<ref name="flettner fl-282v21 kolibri"/> Anton Flettner's partner and confidant was Dr. [[Kurt Hohenemser]], a brilliant and thorough engineer who developed the details necessary for the success of Flettner's helicopters.<ref name="flettner fl-282v21 kolibri"/> Dr. Hohenemser's father was also Jewish, yet both remained unharmed during their tenure together throughout the war as they worked to develop the helicopter for military use.<ref name=largescaleplanes /><ref name="flettner fl-282v21 kolibri"/>
Flettner's helicopter inventions were financed from wealth acquired from his ventilator business, a company that was enhanced by the skill of his wife, Lydia Freudenberg Flettner.<ref name=flettner/> Anton Flettner built his helicopters for the German military, primarily for navy spotter use. Although his wife was Jewish,<ref name="flettner fl-282v21 kolibri">{{cite web|title=The Flettner Fl-282 V21 Kolibri|url=https://sites.google.com/site/skynetairplanes/helicopters/the-flettner-fl-282-v21-kolibri|website=Skynet Airplanes}}</ref> he held a personal relationship with the head of gestapo, [[Heinrich Himmler]]. Himmler had Flettner's wife and family escorted safely to Sweden for the duration of the war.<ref name="flettner fl-282v21 kolibri"/> Anton Flettner's partner and confidant was [[Kurt Hohenemser]], a brilliant and thorough engineer who developed the details necessary for the success of Flettner's helicopters.<ref name="flettner fl-282v21 kolibri"/> Hohenemser's father was also Jewish, yet both remained unharmed during their tenure together throughout the war as they worked to develop the helicopter for military use.<ref name="flettner fl-282v21 kolibri"/>


[[File:Flettner 282 Modell 02.jpg|thumb|right|[[Flettner Fl 282]] "Kolibri" was an early variant of helicopter using two intermeshing rotors|300px]]
[[File:Flettner 282 Modell 02.jpg|thumb|right|[[Flettner Fl 282]] "Kolibri" was an early variant of helicopter using two intermeshing rotors|300px]]


While the final product, the [[Flettner Fl 282|Flettner Fl 282 Kolibri]] ("Hummingbird"), could be factory-assembled, Flettner and Hohenemser insisted that they were the only ones who were capable of assembling the complex [[Intermeshing rotors|intermeshing rotor]] gearbox assembly.<ref name=britannica /> Plans for mass production of 1,000 [[Flettner Fl 282]] helicopters by [[BMW]] were disrupted when allied forces bombed the designated factory.<ref name=largescaleplanes/>
While the final product, the [[Flettner Fl 282|Flettner Fl 282 Kolibri]] ("Hummingbird"), could be factory-assembled, Flettner and Hohenemser insisted that they were the only ones who were capable of assembling the complex [[Intermeshing rotors|intermeshing rotor]] gearbox assembly.<ref name=britannica /> Plans for mass production of 1,000 [[Flettner Fl 282]] helicopters by [[BMW]] were disrupted when allied forces bombed the designated factory.


At least two other Flettner helicopters were under development when World War II ended.<ref name=allaero>{{cite web|title=Flettner Fl 285|url=http://all-aero.com/index.php/contactus/35-helicopters/copters/12377-flettner-fl-285-|website=All-Aero.com|publisher=All Aero}}</ref> They were the [http://all-aero.com/index.php/contactus/35-helicopters/copters/12377-flettner-fl-285- Flettner Fl 285], another reconnaissance helicopter with a two-hour flight limit and capacity to carry two small bombs, and the [http://www.wehrmacht-history.com/luftwaffe/projects/flettner-fl-339-project.htm Flettner Fl 339], a large transport helicopter project designed for approximately 20 passengers.<ref name="allaero" />
At least two other Flettner helicopters were under development when World War II ended.<ref name=allaero>{{cite web|title=Flettner Fl 285|url=http://all-aero.com/index.php/contactus/35-helicopters/copters/12377-flettner-fl-285-|website=All-Aero.com|publisher=All Aero}}</ref> They were the [[Flettner Fl 285]], another reconnaissance helicopter with a two-hour flight limit and capacity to carry two small bombs, and the [[Flettner Fl 339]], a large transport helicopter project designed for approximately 20 passengers.<ref name="allaero" />


== Photo gallery ==
== Photo gallery ==
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Image:Flettner kolibri.gif|Flettner Fl 282 Kolibri
Image:Flettner kolibri.gif|Flettner Fl 282 Kolibri
Image:Eddersheim, Friedhof, Grab Flettner.JPG|Tomb of Anton Flettner
Image:Eddersheim, Friedhof, Grab Flettner.JPG|Tomb of Anton Flettner
Image:Bundesarchiv Bild 102-11248, Berlin, Eröffnung der Automobilausstellung.jpg|1931 photo of the Flettner-Krupp-Grosskraftwagen, the largest German truck, which is 15 tons. The payload and is 14 m long and it is powered by a 150 P.S. engine.
Image:Bundesarchiv Bild 102-11248, Berlin, Eröffnung der Automobilausstellung.jpg|1931 photo of the Flettner-Krupp-Grosskraftwagen, the largest German truck at 14 m long, with a payload capacity of 15 tons, powered by a 147&nbsp;hp engine.
Image:Flettner 282 airborne.jpg|Flettner Fl 282 during flight trials after World War II, with US markings
Image:Flettner 282 airborne.jpg|Flettner Fl 282 during flight trials after World War II, with US markings
</gallery>
</gallery>
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== Post World War II ==
== Post World War II ==
[[File:Flettner+3(~v braun).jpg|thumb|right|250px|Flettner meets [[Wernher von Braun]]]]
[[File:Flettner+3(~v braun).jpg|thumb|right|250px|Flettner meets [[Wernher von Braun]]]]
Upon the war's conclusion, Anton Flettner was held in the "Dustbin" interrogation camp at [[Kransberg Castle]].<ref name="projectpaperclip">{{cite web|title=Project Paperclip|url=https://conflictmatrixstructure.wordpress.com/2013/12/05/project-paperclip/ |website=Conflict Matrix|accessdate=December 5, 2013}}</ref> After 1945, Flettner, along with many other aviation pioneers, was brought to the United States as part of [[Operation Paperclip]].<ref>{{cite book |last=Boyne |first=Walter J. |authorlink=Walter J. Boyne |year=2011 |title=How the Helicopter Changed Modern Warfare |page=45|publisher=Pelican Publishing |isbn=978-1-58980-700-6}}</ref> Flettner and his partner, Dr. [[Kurt Hohenemser]], were among the first German emigrants into the [[United States]] after [[World War II]].<ref name="New York Times">{{cite web|last1=Martin|first1=Douglas |title=Kurt Hohenemser, Early Helicopter Designer, Dies at 95|url=https://www.nytimes.com/2001/04/21/us/kurt-hohenemser-early-helicopter-designer-dies-at-95.html |website=New York Times|publisher=The New York Times|accessdate=April 21, 2001}}</ref>
Upon the war's conclusion, Anton Flettner was held in the "Dustbin" interrogation camp at [[Kransberg Castle]].<ref name="projectpaperclip">{{cite web|title=Project Paperclip|url=https://conflictmatrixstructure.wordpress.com/2013/12/05/project-paperclip/ |website=Conflict Matrix|date=5 December 2013 |access-date=December 5, 2013}}</ref> After 1945, Flettner, along with many other aviation pioneers, was brought to the United States as part of [[Operation Paperclip]].<ref>{{cite book |last=Boyne |first=Walter J. |author-link=Walter J. Boyne |year=2011 |title=How the Helicopter Changed Modern Warfare |page=45|publisher=Pelican Publishing |isbn=978-1-58980-700-6}}</ref> Flettner and his partner, [[Kurt Hohenemser]], were among the first German emigrants into the [[United States]] after [[World War II]].<ref name="New York Times">{{cite news|last1=Martin|first1=Douglas |title=Kurt Hohenemser, Early Helicopter Designer, Dies at 95|url=https://www.nytimes.com/2001/04/21/us/kurt-hohenemser-early-helicopter-designer-dies-at-95.html |work=The New York Times|date=21 April 2001 |access-date=April 21, 2001}}</ref>


Flettner started Flettner Aircraft Corporation, which developed helicopters for the U.S. military.<ref name=britannica />
Flettner started Flettner Aircraft Corporation, which developed helicopters for the U.S. military.<ref name=britannica />
In 1949, Flettner employed [[Kurt Hohenemser]] as a consultant to the Flettner Aircraft Corporation.<ref name="leobaeckinstitute">{{cite web|last1=Glover|first1=Sarah |last2=Rieg-Baumhauer|first2=Felix |title=Guide to the Kurt Hohenemser Collection undated, 1885-2007 (bulk 1931-2001)|url=http://findingaids.cjh.org/?pID=3451727 |website=Leo Back Institute Center for Jewish History|publisher=Leo Baeck Institute}}</ref> Flettner and [[Kurt Hohenemser]], who together developed numerous patents in Germany, kept in close contact after both men emigrated to the [[United States]].<ref name="leobaeckinstitute" />
In 1949, Flettner employed Kurt Hohenemser as a consultant to the Flettner Aircraft Corporation.<ref name="leobaeckinstitute">{{cite web|last1=Glover|first1=Sarah |last2=Rieg-Baumhauer|first2=Felix |title=Guide to the Kurt Hohenemser Collection undated, 1885-2007 (bulk 1931-2001)|url=http://findingaids.cjh.org/?pID=3451727 |website=Leo Back Institute Center for Jewish History|publisher=Leo Baeck Institute}}</ref> Flettner and Kurt Hohenemser, who together developed numerous patents in Germany, kept in close contact after both men emigrated to the United States.<ref name="leobaeckinstitute" />


Flettner's company in the U.S. was not commercially successful, but his work was shared with the [[US Army Air Forces]].<ref name=neam /> Throughout his 14 years in the [[United States]], Flettner was active in carrying out research projects for the [[US Army]], [[US Air Force]], and the [[US Navy]].<ref name="helis" />
Flettner's company in the U.S. was not commercially successful, but his work was shared with the [[US Army Air Forces]].<ref name=neam /> Throughout his 14 years in the United States, Flettner was active in carrying out research projects for the [[US Army]], US Air Force, and the [[US Navy]].<ref name="helis" />


Flettner became the chief designer of [[Kaman Aircraft]] and many of the Flettner design concepts are found in [[Kaman Aircraft|Kaman]] helicopters of later years.<ref name="aeronautical" />
Flettner became the chief designer of [[Kaman Aircraft]] and many of the Flettner design concepts are found in Kaman helicopters of later years.<ref name="aeronautical" />


Today the Flettner rotor is in operation as a supplemental propulsion system for transport and research vessels.<ref name="deutches">{{cite web|title=Flettner Rotors|url=http://www.deutsches-museum.de/en/information/young-people/inventors-trail/drivetrains/flettner-rotor/ |website=Deutsches Museum|access-date=2017-02-28|archive-url= https://web.archive.org/web/20161207121319/http://www.deutsches-museum.de/en/information/young-people/inventors-trail/drivetrains/flettner-rotor/ |archive-date=2016-12-07|url-status=dead}}</ref> There are two ships utilizing the concept of the Flettner rotor in a modified form, the [[turbosail]] Acyone developed by Jacques-Yves Cousteau in 1985 and the [[E-Ship 1]], a cargo ship that made its first voyage in 2010.<ref name="flettner" /><ref name="turbosail">{{cite web|title=Turbosail Cousteau Society|url=http://www.cousteau.org/technology/turbosail/ |website=cousteau.org|publisher=Cousteau |url-status=dead|archiveurl= https://web.archive.org/web/20131218083602/http://www.cousteau.org/technology/turbosail |archivedate=2013-12-18}}</ref><ref name="e-ship1">{{cite web|last1=Gerke|first1=Thomas |title=E-Ship 1 - 21st-Century Sailing|url=https://cleantechnica.com/2012/04/10/e-ship-1-21st-century-sailing/ |website=cleantechnica.com|publisher=Clean Technica|accessdate=April 10, 2012}}</ref> [[Albert Einstein]] praised the Flettner [[Rotor ship]] as having great practical importance.<ref name="britannica" />
Today the Flettner rotor is in operation as a supplemental propulsion system for transport and research vessels.<ref name="deutches">{{cite web|title=Flettner Rotors|url=http://www.deutsches-museum.de/en/information/young-people/inventors-trail/drivetrains/flettner-rotor/ |website=Deutsches Museum|access-date=2017-02-28|archive-url= https://web.archive.org/web/20161207121319/http://www.deutsches-museum.de/en/information/young-people/inventors-trail/drivetrains/flettner-rotor/ |archive-date=2016-12-07|url-status=dead}}</ref> There are two ships utilizing the concept of the Flettner rotor in a modified form, the [[turbosail]] Acyone developed by Jacques-Yves Cousteau in 1985 and the [[E-Ship 1]], a cargo ship that made its first voyage in 2010.<ref name="flettner" /><ref name="turbosail">{{cite web|title=Turbosail Cousteau Society|url=http://www.cousteau.org/technology/turbosail/ |website=cousteau.org|publisher=Cousteau |url-status=dead|archive-url= https://web.archive.org/web/20131218083602/http://www.cousteau.org/technology/turbosail |archive-date=2013-12-18}}</ref><ref name="e-ship1">{{cite web|last1=Gerke|first1=Thomas |title=E-Ship 1 - 21st-Century Sailing|url=https://cleantechnica.com/2012/04/10/e-ship-1-21st-century-sailing/ |website=cleantechnica.com|date=10 April 2012 |publisher=Clean Technica|access-date=April 10, 2012}}</ref> [[Albert Einstein]] praised the Flettner [[Rotor ship]] as having great practical importance.<ref name="britannica" />


Anton Flettner's colleague and former partner, [[Kurt Hohenemser]], worked his remaining years in the [[United States]] to prove Flettner's idea that properly designed flexible helicopter-type rotors are more suitable for producing electricity from the wind than rigid airplane-type rotors.<ref name="New York Times" /> An [http://www.offshorewind.biz/2017/02/21/seawind-olav-olsen-to-jointly-bring-forward-6-2mw-demo-project/ offshore wind energy project] announced in February 2017, involving [[Seawind Ocean Technology]] B.V., aims to demonstrate the wind energy applications put forth by Anton Flettner, [[Kurt Hohenemser]], and [[Glidden Doman]] (American aeronautical engineer) in harsh wind and sea conditions.<ref name="New York Times" /><ref>{{cite web|title=Seawind, Olav Olsen to Jointly Bring Forward 6.2 MW Demo Project|url=http://www.offshorewind.biz/2017/02/21/seawind-olav-olsen-to-jointly-bring-forward-6-2mw-demo-project/ |website=offshoreWIND.biz}}</ref><ref name="seawindhistory">{{cite web|last1=Jakubowski|first1=Martin |title=Seawind History|url=http://seawindtechnology.com/history/ |website=Seawind Technology|publisher=Seawind|accessdate=January 17, 2017|archive-url=https://web.archive.org/web/20170215025059/http://seawindtechnology.com/history/ |archive-date=February 15, 2017|url-status=dead}}</ref><ref name="two hundred twenty one">{{cite web|last1=de Vries|first1=Eize|title=Seawind steps up development of radical two-blade offshore turbine|url=https://www.windpowermonthly.com/article/1678312/seawind-steps-development-radical-two-blade-offshore-turbine |website=Windtech International|publisher=Windtech Offshore|accessdate=July 24, 2020 |archiveurl= https://web.archive.org/web/20200621031512/https://www.windpowermonthly.com/article/1678312/seawind-steps-development-radical-two-blade-offshore-turbine |archivedate=June 21, 2020 |date=April 1, 2020 |url-status=live}}</ref>
Anton Flettner's colleague and former partner, Kurt Hohenemser, worked his remaining years in the United States to prove Flettner's idea that properly designed flexible helicopter-type rotors are more suitable for producing electricity from the wind than rigid airplane-type rotors.<ref name="New York Times" /> An offshore wind energy project announced in February 2017, involving [[Seawind Ocean Technology]] B.V., aims to demonstrate the wind energy applications put forth by Anton Flettner, Kurt Hohenemser, and [[Glidden Doman]] in harsh wind and sea conditions.<ref name="New York Times" /><ref>{{cite web|title=Seawind, Olav Olsen to Jointly Bring Forward 6.2 MW Demo Project|url=http://www.offshorewind.biz/2017/02/21/seawind-olav-olsen-to-jointly-bring-forward-6-2mw-demo-project/ |website=offshoreWIND.biz|date=21 February 2017 }}</ref><ref name="seawindhistory">{{cite web|last1=Jakubowski|first1=Martin |title=Seawind History|url=http://seawindtechnology.com/history/ |website=Seawind Technology|publisher=Seawind|access-date=January 17, 2017|archive-url=https://web.archive.org/web/20170215025059/http://seawindtechnology.com/history/ |archive-date=February 15, 2017|url-status=dead}}</ref><ref name="two hundred twenty one">{{cite web|last1=de Vries|first1=Eize|title=Seawind steps up development of radical two-blade offshore turbine|url=https://www.windpowermonthly.com/article/1678312/seawind-steps-development-radical-two-blade-offshore-turbine |website=Windtech International|publisher=Windtech Offshore|access-date=July 24, 2020 |archive-url= https://web.archive.org/web/20200621031512/https://www.windpowermonthly.com/article/1678312/seawind-steps-development-radical-two-blade-offshore-turbine |archive-date=June 21, 2020 |date=April 1, 2020 |url-status=live}}</ref>


Anton Flettner died at age 76 in New York City on December 29, 1961.<ref>[http://www.hubschraubermuseum.de/archiv/personnlichkeiten/flettner-anton Anton Flettner; Hubschraubermuseum Bückeburg]</ref> Among his many distinctions, Anton Flettner was an honorary member of the [[American Helicopter Society]] and the Convertible Aircraft Pioneers.<ref name="helis" /> Flettner's birthplace home and tomb are national historic protected monuments in Germany.<ref name="flettner" />
Anton Flettner died at age 76 in New York City on December 29, 1961.<ref>{{Cite web |url=http://www.hubschraubermuseum.de/archiv/personnlichkeiten/flettner-anton |title=Anton Flettner; Hubschraubermuseum Bückeburg |access-date=2010-07-07 |archive-date=2018-11-18 |archive-url=https://web.archive.org/web/20181118223140/http://www.hubschraubermuseum.de/archiv/personnlichkeiten/flettner-anton |url-status=dead }}</ref> Among his many distinctions, Anton Flettner was an honorary member of the [[American Helicopter Society]] and the Convertible Aircraft Pioneers.<ref name="helis" /> Flettner's birthplace home and tomb are national historic protected monuments in Germany.<ref name="flettner" />


[[File:Flettner Rotor Aircraft.jpg|thumb|Flettner Rotor Aircraft (The Plymouth A-A-2004)|300px]]
[[File:Flettner Rotor Aircraft.jpg|thumb|A Flettner rotor aircraft (the [[Plymouth A-A-2004]])|300px]]


== Aircraft built by Flettner Flugzeugbau GmbH ==
== Aircraft built by Flettner Flugzeugbau GmbH ==
Line 97: Line 101:
*[[Flettner Fl 265]]<ref name="flugzeugbau" />
*[[Flettner Fl 265]]<ref name="flugzeugbau" />
*[[Flettner Fl 282]]<ref name="flugzeugbau" />
*[[Flettner Fl 282]]<ref name="flugzeugbau" />
*[http://all-aero.com/index.php/contactus/35-helicopters/copters/12377-flettner-fl-285- Flettner Fl 285]<ref name="flugzeugbau" />
*[[Flettner Fl 285]]<ref name="flugzeugbau" />
*[http://www.wehrmacht-history.com/luftwaffe/projects/flettner-fl-339-project.htm Flettner Fl 339]<ref name="flugzeugbau" />
*[[Flettner Fl 339]]<ref name="flugzeugbau" />


== See also ==
== See also ==
Line 108: Line 112:
* [[Flettner Fl 265]] helicopter
* [[Flettner Fl 265]] helicopter
* [[Flettner Fl 282]] "Kolibri" helicopter
* [[Flettner Fl 282]] "Kolibri" helicopter
* [http://www.flettner.co.uk/ Flettner ventilator]
* [[Gyrodynes and Heliplanes]]
* [[Gyrodynes and Heliplanes]]
* [[Charles Kaman]]
* [[Charles Kaman]]
Line 134: Line 137:
[[Category:1885 births]]
[[Category:1885 births]]
[[Category:1961 deaths]]
[[Category:1961 deaths]]
[[Category:Aviation pioneers]]
[[Category:German aviation pioneers]]
[[Category:German emigrants to the United States]]
[[Category:Emigrants from Allied-occupied Germany]]
[[Category:German people of World War II]]
[[Category:German people of World War II]]
[[Category:German aerospace engineers]]
[[Category:German aerospace engineers]]
[[Category:German inventors]]
[[Category:20th-century German inventors]]
[[Category:People from Main-Taunus-Kreis]]
[[Category:People from Main-Taunus-Kreis]]
[[Category:20th-century inventors]]
[[Category:Engineers from Hesse]]
[[Category:Engineers from Hesse]]

Latest revision as of 03:45, 19 September 2024

Anton Flettner
Anton Flettner
Born1 November 1885
Died29 December 1961 (1961-12-30) (aged 76)
NationalityGerman
OccupationEngineer
Engineering career
DisciplineAviation Engineer, Inventor
ProjectsHelicopters, Rotor Ships

Anton Flettner (1 November 1885 – 29 December 1961) was a German aviation engineer and inventor.[1] Born in Eddersheim (today a district of Hattersheim am Main), Flettner made important contributions to airplane, helicopter, vessel, and automobile designs.[1][2][3]

After serving Germany in both World Wars, Anton Flettner emigrated to the United States post World War II as a consultant to the office of Naval Research at the United States Navy.[4]

Anton Flettner attended the Fulda State Teachers College in Fulda, Germany.[5] He was the village teacher in Pfaffenwiesbach from 1906 to 1909.[4] Flettner subsequently taught high school mathematics and physics in Frankfurt, where he developed ideas that would assist Germany in World War I.[5]

Flettner developed a new method of harnessing the wind: the Flettner Rotor ship. It could permit ocean liners to reduce their crews by two-thirds and save 90 percent in fuel.[6][7]

World War I

[edit]

From 1914 to 1918 Anton Flettner worked at the German Ministry for War in the development of remote controls for air, water, and land vehicles.[8] While employed under the aegis of Graf Zeppelin, Flettner also developed pilotless aircraft projects.[1]

At the age of 29, Flettner presented his first invention, a steerable torpedo, to the Kriegsmarine (German Imperial Navy) of World War I.[2] This, and his next invention, a remote-controlled combat car, which was presented to the Heer (German Army), were rejected because they were not considered to be technically feasible.[2] However, Flettner's efforts culminated in the prototype Siemens Schuckert Werke 1000 kg wire guided air to surface missile of 1918.

During World War I, Flettner developed the servo tab / anti-servo tab.[9][10] The servo tab evolved into the "trim tab" which is still in use on all airplanes and many large vessels.[1][9] Trim tabs are extremely useful in moving large rudders on vessels with vastly reduced power.[1][9]

The Flettner rotor ship Buckau

Savonius collaboration

[edit]

In 1923, Finnish architect Sigurd Johannes Savonius took interest in Flettner's rotor ship, and the two began a collaboration. By the next year, the architect had invented the Savonius wind turbine, and by 1930 had patented a ventilation device based on the wind turbine.[11] The patent was later acquired by Flettner's firm Flettner Ventilator Limited, which still manufactures modern versions of the device in Britain.[12][13] It has been widely used on buses, vans, boats, railroad cars, campervans, and trucks to assist cooling in warm weather.

Other post-World-War-I work

[edit]

Following World War I, Flettner was named managing director of the Institute for Aero and Hydro Dynamics in Amsterdam.[4] He held that post until 1931.[4]

With assistance from German physicist Albert Betz, Swiss aeronautical engineer Jakob Ackeret, German engineer Ludwig Prandtl and German theoretical physicist Albert Einstein, Anton Flettner constructed an experimental rotor vessel, the Buckau, later renamed the Baden-Baden, in October 1924 at the Friedrich Krupp Germaniawerft.[14] The Buckau was a schooner refitted with two rotating 50-foot cylinders and was the first vessel built with a propulsion system based on the Magnus effect.[14] Flettner came upon the idea while at the beach with his wife.[7] Flettner used sand, flowing over his rotating hand, to describe the Magnus effect and realized its potential for sail propulsion.[7] The Baden-Baden crossed the Atlantic in 1926.[4] It could outsail normal schooners under moderate to heavy winds, but was destroyed by a storm in 1931.[15] A commercial rotor ship, the Barbara, was also built, and sailed to the United States.[15]

In 1926, Anton Flettner shifted his focus to aviation in founding his own company, the Anton Flettner Aircraft Corporation in Berlin, aiming at the application of the Flettner-rotor as a wing replacement on large wind turbines.[8][9] In 1935, Flettner built a German night reconnaissance and anti-submarine autogyro called the Fl 184.[9][16] Flettner followed this accomplishment by building the Flettner Fl 185 in 1936, an experimental German gyrodyne, which could fly as both a helicopter and as a gyroplane.

In 1938 Flettner, together with Kurt Hohenemser, built the Flettner Fl 265.[2] The Flettner Fl 265 as the likely pioneering example of a twin-lift rotor synchropter, addressed the problem of torque compensation as the first helicopter with intermeshing rotors (Flettner double rotor).[2]

Flettner Fl 265 model

World War II

[edit]

During World War II, Anton Flettner headed Flettner Flugzeugbau GmbH, which specialized in reconnaissance helicopters for the German Luftwaffe (Air Force).[1]

Flettner's helicopter inventions were financed from wealth acquired from his ventilator business, a company that was enhanced by the skill of his wife, Lydia Freudenberg Flettner.[2] Anton Flettner built his helicopters for the German military, primarily for navy spotter use. Although his wife was Jewish,[17] he held a personal relationship with the head of gestapo, Heinrich Himmler. Himmler had Flettner's wife and family escorted safely to Sweden for the duration of the war.[17] Anton Flettner's partner and confidant was Kurt Hohenemser, a brilliant and thorough engineer who developed the details necessary for the success of Flettner's helicopters.[17] Hohenemser's father was also Jewish, yet both remained unharmed during their tenure together throughout the war as they worked to develop the helicopter for military use.[17]

Flettner Fl 282 "Kolibri" was an early variant of helicopter using two intermeshing rotors

While the final product, the Flettner Fl 282 Kolibri ("Hummingbird"), could be factory-assembled, Flettner and Hohenemser insisted that they were the only ones who were capable of assembling the complex intermeshing rotor gearbox assembly.[1] Plans for mass production of 1,000 Flettner Fl 282 helicopters by BMW were disrupted when allied forces bombed the designated factory.

At least two other Flettner helicopters were under development when World War II ended.[18] They were the Flettner Fl 285, another reconnaissance helicopter with a two-hour flight limit and capacity to carry two small bombs, and the Flettner Fl 339, a large transport helicopter project designed for approximately 20 passengers.[18]

[edit]

Post World War II

[edit]
Flettner meets Wernher von Braun

Upon the war's conclusion, Anton Flettner was held in the "Dustbin" interrogation camp at Kransberg Castle.[19] After 1945, Flettner, along with many other aviation pioneers, was brought to the United States as part of Operation Paperclip.[20] Flettner and his partner, Kurt Hohenemser, were among the first German emigrants into the United States after World War II.[21]

Flettner started Flettner Aircraft Corporation, which developed helicopters for the U.S. military.[1] In 1949, Flettner employed Kurt Hohenemser as a consultant to the Flettner Aircraft Corporation.[22] Flettner and Kurt Hohenemser, who together developed numerous patents in Germany, kept in close contact after both men emigrated to the United States.[22]

Flettner's company in the U.S. was not commercially successful, but his work was shared with the US Army Air Forces.[9] Throughout his 14 years in the United States, Flettner was active in carrying out research projects for the US Army, US Air Force, and the US Navy.[4]

Flettner became the chief designer of Kaman Aircraft and many of the Flettner design concepts are found in Kaman helicopters of later years.[8]

Today the Flettner rotor is in operation as a supplemental propulsion system for transport and research vessels.[23] There are two ships utilizing the concept of the Flettner rotor in a modified form, the turbosail Acyone developed by Jacques-Yves Cousteau in 1985 and the E-Ship 1, a cargo ship that made its first voyage in 2010.[2][24][25] Albert Einstein praised the Flettner Rotor ship as having great practical importance.[1]

Anton Flettner's colleague and former partner, Kurt Hohenemser, worked his remaining years in the United States to prove Flettner's idea that properly designed flexible helicopter-type rotors are more suitable for producing electricity from the wind than rigid airplane-type rotors.[21] An offshore wind energy project announced in February 2017, involving Seawind Ocean Technology B.V., aims to demonstrate the wind energy applications put forth by Anton Flettner, Kurt Hohenemser, and Glidden Doman in harsh wind and sea conditions.[21][26][27][28]

Anton Flettner died at age 76 in New York City on December 29, 1961.[29] Among his many distinctions, Anton Flettner was an honorary member of the American Helicopter Society and the Convertible Aircraft Pioneers.[4] Flettner's birthplace home and tomb are national historic protected monuments in Germany.[2]

A Flettner rotor aircraft (the Plymouth A-A-2004)

Aircraft built by Flettner Flugzeugbau GmbH

[edit]

See also

[edit]

References

[edit]
  1. ^ a b c d e f g h i "Anton Flettner". The New York Times (Obituary). December 30, 1961.
  2. ^ a b c d e f g h "FLETTNER, Anton aus Eddersheim am Main". duchmann.net. Duchmann.
  3. ^ "Flettner Ventilator". flettner.co.uk.
  4. ^ a b c d e f g Graven, Eric. "Anton Flettner". Helis.com. The New York Times.
  5. ^ a b Lepage, Jean-Denis G.G. (February 5, 2009). Aircraft of the Luftwaffe, 1935D1945: An Illustrated Guide. McFarland. pp. 23–24. ISBN 978-0786439379.
  6. ^ "Mein Weg zum Rotor". abebooks.com. F.O. Willhoft.
  7. ^ a b c Seybold, G.B. "A Sailing Ship Without Sails: New Wonder of the Seas". Popular Science Monthly. February 1925.
  8. ^ a b c Hirschel, Ernst Heinrich; Prem, Horst; Madelung, Gero (2012-12-06). Aeronautical Research in Germany: From Lilienthal until Today. Springer. ISBN 9783642184840.
  9. ^ a b c d e f "Anton Flettner". NEAM.
  10. ^ "ANTOH FLETTNER, INVENTOR, WAS 76; Developer of Controls Used in Ships and Planes Dies". The New York Times. 30 December 1961. Retrieved 11 September 2024.
  11. ^ Sigurd J. Savonius. "Durch Luftströmung angetriebene Vorrichtung zur Ventilation von geschlossenen Räumen oder zur Verbesserung, bezw. Erhaltung eines Schornsteinzuges".
  12. ^ Flettner Ventilator Limited
  13. ^ Borg, John (1985). "The Magnus Effect - an overview of its past and future practical applications" (PDF). Defense Technical Information Center (.mil). Prepared by the Borg/Luther Group for Naval Sea Systems Command Department of the Navy. Retrieved 11 September 2024.
  14. ^ a b "History of windpower". Thiiink.com.
  15. ^ a b "Anton Flettner's first rotor ship, the Baden-Baden, crossed the Atlantic in 1926". Researchgate.net.
  16. ^ "Flettner Fl 184 reconnaissance helicopter, prototype". newingtonwarmuseum.com. Newington War Museum.
  17. ^ a b c d "The Flettner Fl-282 V21 Kolibri". Skynet Airplanes.
  18. ^ a b "Flettner Fl 285". All-Aero.com. All Aero.
  19. ^ "Project Paperclip". Conflict Matrix. 5 December 2013. Retrieved December 5, 2013.
  20. ^ Boyne, Walter J. (2011). How the Helicopter Changed Modern Warfare. Pelican Publishing. p. 45. ISBN 978-1-58980-700-6.
  21. ^ a b c Martin, Douglas (21 April 2001). "Kurt Hohenemser, Early Helicopter Designer, Dies at 95". The New York Times. Retrieved April 21, 2001.
  22. ^ a b Glover, Sarah; Rieg-Baumhauer, Felix. "Guide to the Kurt Hohenemser Collection undated, 1885-2007 (bulk 1931-2001)". Leo Back Institute Center for Jewish History. Leo Baeck Institute.
  23. ^ "Flettner Rotors". Deutsches Museum. Archived from the original on 2016-12-07. Retrieved 2017-02-28.
  24. ^ "Turbosail Cousteau Society". cousteau.org. Cousteau. Archived from the original on 2013-12-18.
  25. ^ Gerke, Thomas (10 April 2012). "E-Ship 1 - 21st-Century Sailing". cleantechnica.com. Clean Technica. Retrieved April 10, 2012.
  26. ^ "Seawind, Olav Olsen to Jointly Bring Forward 6.2 MW Demo Project". offshoreWIND.biz. 21 February 2017.
  27. ^ Jakubowski, Martin. "Seawind History". Seawind Technology. Seawind. Archived from the original on February 15, 2017. Retrieved January 17, 2017.
  28. ^ de Vries, Eize (April 1, 2020). "Seawind steps up development of radical two-blade offshore turbine". Windtech International. Windtech Offshore. Archived from the original on June 21, 2020. Retrieved July 24, 2020.
  29. ^ "Anton Flettner; Hubschraubermuseum Bückeburg". Archived from the original on 2018-11-18. Retrieved 2010-07-07.
  30. ^ a b c d e f "Flettner Flugzeugbau GmbH". Wehrmacht History.
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